1. Field of the Invention
The present invention relates to an exchangeable, composite and integrated ink-tank cartridge which is connected to an ink-jet head and storing an ink to be supplied thereto, and an ink-jet recording apparatus employing the ink-tank cartridge. The present invention further relates to an ink-tank cartridge having a specific internal structure, provides an ink jet head and a printer which use the ink-tank cartridge, and is applicable for recording apparatuses such as copy machine, facsimile and so forth, communication apparatuses, office work apparatuses, composite apparatuses, printer and so forth, employing an ink-jet technologies.
2. Description of the Related Art
In the recent years, ink-jet recording apparatus have been progressively made compact and have been proposed in variety of configurations adapting to manner of use in personal basis. In particular, in the case of the recording apparatus for personal use, such a type of apparatus employing an integrated exchangeable cartridge, in which a recording head portion and an ink tank portion are integrated as a single unit, is becoming a preferred configuration for compact construction and low cost. In such apparatus, monochrome recording (principally recording characters) type apparatus employing only black ink have been majority. However, even in such apparatus for personal use, variety of manners of use have been developed to raise demand for color recording (including multi-tone recording) or full-color recording.
Most easy construction for performing such color recording is to prepare necessary number of carriage mounting head-tank integration type cartridge, and to mount the head-tank integration type cartridges filled with necessary color inks on the carriages. In such construction, the carriage is, however, required for each of the head-tank integration type cartridge to be mounted to make the entire apparatus bulky.
On the other hand, Japanese Patent Application Laying-open No. 198861/1990 proposes an ink tank cartridge, in which the recording head portion and the ink tank portion can be separated in order to effectively use a recording head which has much longer life than ink contained in an ink tank. Also, in the above-identified publication, there is proposed an integrated construction of an ink tank cartridge portion for four colors (yellow, magenta, cyan and black) for performing color recording.
However, in such four colors integrated type ink tank cartridge, frequencies of use of the colors are differentiated depending upon an image for color recording. Typically, consuming rate of black ink in formation of the image is higher than those of other color inks, it is inherent to exchange the ink tank cartridge while inks other than black are remained in significant amount.
On the other hand, such exchangeable type ink tank, increased frequency of exchanging of the ink tank should cause increasing of amount of bubble externally penetrating into the ink-jet recording head and a joint portion of the ink tank. Such bubble tends to increase of instability of jetting in the ink-jet recording head.
Also, greater frequency of exchanging of the ink-jet recording head increases possibility of damaging a filter provided in the joint portion between the ink-jet recording head and the ink tank.
Furthermore, in the case of multi-density recording, inks having different densities are employed for image recording to realize multiple gray scale. In this case, frequency of pale ink for forming a highlight portion of the image becomes high to cause similar problem to the color recording.
On the other hand, in consideration of more customization in personal use, use of special color should be taken into account. In such case, the preliminarily packaged ink tank cartridge should not satisfy the demand for use of the special color.
Through study of internal construction of the ink tank cartridge with respect to the overall structure, there is no effective prior art documents in viewpoint of exchanging ability or down-sizing of the apparatus. As a prior art document, Japanese Patent Application Laying-open No. 522/1990 discloses a cartridge employing a construction, in which the ink cartridge is substantially adapted to only store the ink, in relation to the overall construction. The document discloses an integrated ink cartridge which has a primary ink storage portion positioned at upper side and only storing a large amount of ink, an ink-jet recording head positioned at lower side, and a little porous member positioned between the ink-jet recording head and the ink storage portion. The disclosed invention features in that since the porous member is not enclosed within the ink storage portion and arranged only in the ink flow path, use efficiency of the ink is improved. In addition, by defining a secondary ink storage portion as a space for storing the ink at the side of the porous member, a negative pressure exerted to the recording head during recording can be maintained substantially constant by storing the ink flowing from the primary ink storage portion due to expansion of air within the primary ink storage portion upon rising of the temperature (lowering of the pressure).
However, in the invention disclosed in the above-identified document, the porous member is excessively wetted by the ink from the primary ink storage portion positioned at the upper side and storing a large amount of ink, the porous member per se have substantially no negative pressure. Therefore, the ink may spills through an orifice of the ink-jet recording head even at small impact. Therefor, the disclosed ink cartridge is not suitable for practical use. In addition, when the exchangeable ink cartridge, in which the ink container is installed to the ink recording head, is applied to the disclosed construction, it may cause spill out of the ink through the porous member and thus cannot be applicable in practical use.
On the other hand, an ink cartridge, in which the ink is enclosed in a bag and the bag is associated with a spring construction for maintaining the negative pressure in the bag constant, has been knows. However, such construction is expensive. Furthermore, it is difficult to manufacture the spring construction with maintaining the performance thereof.
In any case, as the ink cartridge of prior art for the ink-jet (non-contact recording type) recording apparatus which is reasonable in price and satisfactory in technical level, have not been available.
The applicant had made study for the following items in addition to the problems in the exchanging of the ink tank in the prior art. As an ink container suitable for application in a technical field of the ink jet printer, is required to smoothly supply the ink in corresponding amount to that ejected from the recording head during printing, and not to cause leakage of the ink while not in use. Study has been made in the viewpoint for satisfying both requirement. As a result of study, it has been found that it is important premise for the characteristics of the ink-jet to have a construction including a first storage portion housing a negative pressure generating member and having an atmosphere communicating portion communicated to the atmosphere, and a second storage portion communicated with the first storage portion and directly storing the ink for supplying to the first storage portion in substantially enclosed condition, as a basic construction.
On the other hand, the applicant has made review about technical uniqueness of the ink jet printer field by studying contact type recording technology different from the technical field, in which the present invention is involved. Typically, a pen for a recording equipment for performing recording by contacting with a recording medium, supplies the ink for a recording core having ink absorbing ability and ink holding ability. Therefore, this type of recording core is premised to be exposed to the atmosphere and thus inherently requires an ink impregnating body held in saturated condition with the ink in the region directly contacting with the recording core. Namely, the contact recording technology is thoroughly different from the technical content of the ink jet field.
Through a search, Japanese Utility Model Application Laying-open No. 16385/1982 has been uncovered. This publication discloses a pen for a recording equipment taking a premise of employment of a recording core (porous ink absorbing core) for contacting on the recording medium to perform recording.
The invention disclosed in the above-identified publication includes a first absorbing member contacting with a recording core placed at the lower side and a second absorbing member slightly absorbing the ink at the side communicating with the atmosphere but having lower ink absorbing characteristics than the first absorbing member, and also includes a center chamber projecting the recording core downwardly and an enclosed ink storage chamber for supplying the ink at both sides of the center chamber, as essential elements. With the disclosed construction, when the environmental temperature rises to cause expansion of the air in the enclosed ink storage chamber to flow out the ink, the ink reaches the first absorbing member and the extra amount of ink which cannot be held by the first absorbing member may be absorbed by the second absorbing member so that the ink may not spilled from the recording core. The above-identified publication further discloses a given width of groove extending between lowermost end to uppermost end of a side surface different from a partitioning wall between the central chamber and the enclosed ink storage chamber for relieving extra volume of air generated due to thermal expansion to the atmosphere communication opening when one of two enclosed ink storage chamber becomes empty to store only air.
The inventors made attempt to apply the tank construction set forth above to the non-contact recording type ink-jet head which has a little technical similarity, and found new problem of spilling out of ink through the atmosphere communication opening according to variation of the environmental condition. Furthermore, the first absorbing member as the ink impregnating body in saturating condition with the ink loaded in the region to directly contact with the recording core is not require negative pressure and thus is not in common to the ink-jet technology. Such new problem has not been recognized in the field of pen for the recording equipment and has no technical suggestion for stabilizing the negative pressure.
It is further confirmed that the given width of the groove in the above-identified publication has the function for promoting discharging the air together with the ink so that it may further promote spilling out the ink through the atmosphere communication port. Furthermore, ink consumption from the ink storage chambers at both sides are not even. Therefore, it becomes impossible to perform ink-jet recording once the ink in one of the ink storage chamber is spent out, despite of the fact that relatively large amount of ink is remained in the other ink storage chamber. This clearly wastes ink in the ink storage chamber and borders achievement of the task of the ink-jet technology. This problem is caused by penetration of a large amount of air in the first absorbing member resulting in blocking of supply of the ink.
There is a commonly assigned invention directed to a novel ink-tank cartridge which can solve the problems set out above. The invention is to provide an effective function for the ink jet in the base construction including the first storage chamber housing the negative pressure generating member and having the atmosphere communicating portion for communicating with the atmosphere, and the second storage chamber communicating with the first storage chamber with substantially maintaining the enclosed condition and directly storing the ink to be supplied to the first storage chamber. With the proposed construction, since the tank body has a construction to maintain the negative pressure substantially constant in the most period from initiation of use of the ink cartridge to the end of use, it becomes possible to provide the replaceable ink cartridge, the ink-jet head and the printer suitable for relatively high speed recording.
The inventors of the present invention have attempted to provide an ink tank cartridge which can improve an ink storage chamber of a carriage mount type ink tank cartridge having the construction in commonly assigned invention, and permits further down-sizing of an ink-jet apparatus. In the attempt, when a further ink storage chamber is added to the ink tank having the first and second storage chambers, the size of the apparatus is increased if the additional ink chamber is provided at the rear side of an ink supply portion. On the other hand, when the additional ink chamber is provided at the lower side of the ink supply portion, the amount of the ink to be remained in the additional ink chamber is increased. Furthermore, when the additional ink chamber is provided at the upper side, ink supply speed corresponding to water head difference between the ink in the first storage chamber and the enclosed second storage chamber and the ink in the additional ink chamber upon gas-liquid exchange so as to make ink supply unstable due to leakage of the ink and variation of the ink absorbing region in the absorbing body when environmental condition is varied.